1. Field of the Invention
The present invention relates to an optical information recording and reproducing apparatus which records and reproduces information data on an optical recording medium.
2. Description of the Related Art
An optical disk used as an optical recording medium includes a transparent substrate of a predetermined thickness for covering and protecting the recording surface of the disk. An optical information recording and reproducing apparatus executes reading and recording of information data with respect to the optical disk by irradiating a reading beam or a recording beam on the recording surface through the transparent substrate of such an optical disk.
However, the occurrence of aberrations such as a spherical aberration and frame aberrations generates a problem which decreases the recording and reproducing accuracy of information data.
For example, it is difficult to form the thicknesses of the transparent substrates of all optical disks to be of a predetermined value during manufacture of the disks, and typically, thickness errors of several tens of xcexcm may arise. Further, a disk having a plurality of recording layers, for example, DVD (Digital Versatile Disk), has different thicknesses in the transparent substrate from the surface of the disk to each recording layer. As a result, a spherical aberration is generated by the thickness error in such a transparent substrate, and this aberration decreases the accuracy of the recording and reproducing of information data.
The present invention has been made to solve such problems, and the object of the present invention is to provide an optical information recording and reproducing apparatus which is capable of recording and reproducing information data accurately with respect to an optical recording medium.
An optical information recording and reproducing apparatus according to the present invention which executes recording and reproducing of information data with respect to an optical recording medium, comprises an optical system for photoelectrically converting a reflected light from said optical record medium into a conversion signal, while irradiating a recording surface of said optical recording medium with a laser beam; an aberration correction part for correcting an aberration of said optical system; an aberration correction completion determining part for determining whether or not an operation of an aberration correction by said aberration correction part was completed based on the level of said conversion signal; and a controller for starting a recording operation or a reproducing operation if it is determined that the operation of said aberration correction was completed by said aberration correction completion determining part, while changing an amount of said aberration correction.